1. Field of the Invention
The present invention relates to revascularization of coronary and peripheral arteries through catheter apparatus for treating coronary stenosis and for reestablishing and maintaining coronary circulation and, more particularly, to a highly flexible hollow core coaxial cable for supporting and energizing an electrically or radiant energy heated probe or balloon or fluid inflated balloon, while simultaneously maintaining blood flow and fiber optics provisions.
2. Description of the Prior Art
Cardiovascular restriction or occlusion due to coronary artery disease and peripheral vascular disease may be addressed by any of a number of medical procedures. Pharmacological approaches for inducing dilation of the blood vessels are of a temporary nature and may have undesirable secondary results. Surgical techniques include coronary bypass surgery involving implantation of substitute blood vessels to bypass blood flow around the blockage; as with any major surgery, substantial risks are involved. Recent improvements in laser technology have resulted in development of the capability to medically insert a laser delivery fiber optic close to the blockage to permit lasing the blockage. Such lasing may vaporize, segment or otherwise disengage plaque from the artery. An inflatable balloon may be used to maintain the laser emitting fiber optic end close to the blockage and to widen the artery. Such coronary laser angioplasty procedures and equipment suffer from several significant drawbacks. The particulate matter disengaged will become suspended in the blood stream and may become relocated elsewhere. The extraordinarily high and uncontrolled heat from the laser beam or laser heated tip may permanently damage the artery wall or nearby tissue. The disposable and non disposable parts of the apparatus are very expensive. Danger also exists from laser perforation of the blood vessel wall.
Radio frequency (RF) energy has been discharged from the discharge end of a catheter to electro abrade arterial plaque. The lack of control of the amount of energy radiated poses a serious threat to cardiovascular integrity and to damage of even surrounding tissue. Alternatively, RF has been used to heat the tip of a catheter, which heated catheter is used to thermally mold and displace the plaque. To be effective, sufficient power must be applied to overcome the damping effects of blood flow rate, the distance between the source of RF radiation or hot tip and the plaque, the thickness of the plaque, the extent of fatty tissue, etc.; where these damping factors are minimal, cardiovascular damage is probable. Alternatively, a two electrode device for transmitting RF (discharging) energy therebetween has been used at a specific location adjacent one of the electrodes. The high uncontrolled concentration of heat poses a serious threat of cardiovascular damage.
Ultrasonic techniques have been used to emulsify or fragment arterial plaque. In conjunction therewith, an aspiration tube may be employed to remove the fragmented plaque.
Recent techniques suggest the use of heating liquids adjacent arterial plaque by a chemical exothermic reaction.